I like this style of analysis, but I disagree with your conclusion. There's a few intermediate levels I'd also put in there, each of them a filter in their own way.
There's whatever fueled the Cambrian explosion of diverse animal lifeforms (some say "multicellular life" but I'm not sure about that as multicellularity has evolved independently "at least 46 times" according to Wiki) - this took billions of years so we can classify that as "hard".
Then there's "intelligent enough to solve problems and be self-aware" - dog level intelligence. This is relatively common on Earth, so we can call that "easy".
Then, as you say, there's "culture and language" (language implying at least a certain level of abstract thought), which are not unique to humans (other primates, corvids, orcas, and elephants spring to mind) but is quite rare. Still, it's evolved several times independently (and there were pack hunters even among dinosaurs that may have qualified), so perhaps we can file that under "not numerically common, but inevitable given time".
Then, at last, there's "technological" - it's not at all clear what the qualitative adaptation is there, though I would suspect some sort of runaway sexual selection fixated on abstract thought beyond what is strictly required for survival. That's kind of a freak event, but on the other hand sexual selection as a whole isn't that rare and it fixates on all kinds of things. And of course, it happened a few hundred million years after the Cambrian explosion, and maybe only a few tens of millions of years after evolution got far enough to give us culture and language etc. So maybe this is also a "give it time" kind of thing. A plausible stat would be 1% of cultured, language-using species ending up technological. Not super common, but neither a unicorn event. We just happen to be the first.
Now bearing in mind that the lifespan of a star like ours is roughly 10 billion years, it seems to me like overwhelmingly the hardest thing in all this is making the jump from just slime growing on everything, to little animals running around eating each other, before the star dies. That jump took billions of years for us, and everything after that has happened stupendously quickly by comparison.
My personal opinion for the "great filter"? A combination of "life-bearing planets are rare", "animals are rare", and "technological civilizations don't make it to space for reasons unknown" (either lack of will or more likely self destruction).
There's whatever fueled the Cambrian explosion of diverse animal lifeforms (some say "multicellular life" but I'm not sure about that as multicellularity has evolved independently "at least 46 times" according to Wiki) - this took billions of years so we can classify that as "hard".
Then there's "intelligent enough to solve problems and be self-aware" - dog level intelligence. This is relatively common on Earth, so we can call that "easy".
Then, as you say, there's "culture and language" (language implying at least a certain level of abstract thought), which are not unique to humans (other primates, corvids, orcas, and elephants spring to mind) but is quite rare. Still, it's evolved several times independently (and there were pack hunters even among dinosaurs that may have qualified), so perhaps we can file that under "not numerically common, but inevitable given time".
Then, at last, there's "technological" - it's not at all clear what the qualitative adaptation is there, though I would suspect some sort of runaway sexual selection fixated on abstract thought beyond what is strictly required for survival. That's kind of a freak event, but on the other hand sexual selection as a whole isn't that rare and it fixates on all kinds of things. And of course, it happened a few hundred million years after the Cambrian explosion, and maybe only a few tens of millions of years after evolution got far enough to give us culture and language etc. So maybe this is also a "give it time" kind of thing. A plausible stat would be 1% of cultured, language-using species ending up technological. Not super common, but neither a unicorn event. We just happen to be the first.
Now bearing in mind that the lifespan of a star like ours is roughly 10 billion years, it seems to me like overwhelmingly the hardest thing in all this is making the jump from just slime growing on everything, to little animals running around eating each other, before the star dies. That jump took billions of years for us, and everything after that has happened stupendously quickly by comparison.
My personal opinion for the "great filter"? A combination of "life-bearing planets are rare", "animals are rare", and "technological civilizations don't make it to space for reasons unknown" (either lack of will or more likely self destruction).